Flyover subdomain detection.

dnsSUBflyover.sh

#!/bin/env bash
# Checks if subdomain.$1 is registered.
# Iterates the 1000 most popular subdomains.
#   NOTE: Can be changed to 10000, or even 100000.
#
# Usage:
#   ./dnsSUBflyover.sh nike.com
#
# NOTE:
#   For more subdomains:
#     https://github.com/YashGoti/Subdomain
#     https://github.com/aboul3la/Sublist3r
# ----------------------------------


if [ "$#" == "0" ]; then
    echo "Exactly one argument required! EG: nike.com"
    exit 1
fi

# https://github.com/bitquark/dnspop/blob/master/results/bitquark_20160227_subdomains_popular_1000
SUBS=($(
         printf ' '
         while read sub; do
           printf "${sub,,} "
         done <<< $(curl -sS "https://raw.githubusercontent.com/bitquark/dnspop/master/results/bitquark_20160227_subdomains_popular_1000")
       )
     )

ELEMENTS=${#SUBS[@]}

while (( "$#" )); do
  for (( i=0;i<$ELEMENTS;i++)); do
    dig ${SUBS[${i}]}.$1 +short | grep -v -e '^$' > /dev/null && echo "${SUBS[${i}]}.$1 : registered"
  done
shift

done